Acanthamoebic keratitis is an important corneal disease which may cause severe complication. The difficulty in diagnosis, the difficulty in treatment, and the long treatment process are factors leading to the poor prognosis of these patients. In this retrospective study, the investigators try to analyze the tissue proven Acanthamoebic keratitis diagnosed in our hospital. The investigators will focus on the in vivo confocal microscopic results, the medical history and the medical/surgical treatment outcome. The investigators will collect the tissue proven cases according to the data provided by laboratory diagnosis department and pathological department. The in vivo confocal microscopic results will be collected and analyzed. The investigators will also look through the photography of the external eyes from data stored in PAC system. The medical history and treatment outcome will be studied from clinical chart review. From this study, the investigators aimed to find out a easy way of diagnosing Acanthamoebic keratitis from in vivo confocal microscopy, and find out a better way for treatment.